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I'm new to this fantastic forum. Thanks.
My wife is adamant that our oven will feature a clay dome as the main cooking area thermal mass. She doesn't want cement in her oven apparently.
I'm not so keen on the aesthetics of completely rustic cob built ovens and their problems with the bad weather we have here.
We are building in the back yard on a raised area partly beneath a canopy.
That means our cooking space is very near to the door to the kitchen and is undercover, which is great.
I think I can get away without building a further base as we are going onto stone and concrete flags on mortar and hardcore.
Because of the location we have a canopy to avoid with the flue so will need to duct from the ideal front position to the middle the dome where it will clear the canopy.
An easy option would be to build a cob oven and enclose it in a 'kennel' to weatherproof it and hide any ugly flue routing we might have to do, with loose fill insulation.
Unfortunately we don't quite have the space at the back of the oven for an enclosure without interfering with existing hard landscaping.
I am proposing hybrid design, using a basic 2:1 sand:fireclay mix 'cast' over a sandcastle dome form to create a 55mm thick oven inner.
This will be sitting on standard 64mm firebricks on 50mm ceramic board insulation.
The clay thermal mass layer would be dried completely before adding 25-50mm ceramic blanket insulation and a layer of cement + aerated clay 'aeorcrete' for more insulation and protection.
The outer layer would be 100mm thick and incorporate ducting the flu from the ideal position up to the top of the dome and a twin wall chimney.
If I am able to get this layer tidy and waterproof I would not add any render. If needs be the whole thing will also be rendered.
I am hopeful I can make the aerocrete layer so that it could be removed if we had cast replacement clay dome.
As I understand it because of the shrinkage of clay ovens and the fact that they aren't actually fired at ceramic temperatures it is normal to add any outer layers before the inner has dried and let thewole lot slowly dry out together. I am hoping that by 'uncoupling' the clay layer from the concrete outer with the ceramic blanket I can wait until the clay has done all of it's shrinking before moving on to create the outer layer, thereby having more control of dimensions.
Apologies for the long first post. I have attached a sketch of the design and welcome comments and advice.
My wife is adamant that our oven will feature a clay dome as the main cooking area thermal mass. She doesn't want cement in her oven apparently.
I'm not so keen on the aesthetics of completely rustic cob built ovens and their problems with the bad weather we have here.
We are building in the back yard on a raised area partly beneath a canopy.
That means our cooking space is very near to the door to the kitchen and is undercover, which is great.
I think I can get away without building a further base as we are going onto stone and concrete flags on mortar and hardcore.
Because of the location we have a canopy to avoid with the flue so will need to duct from the ideal front position to the middle the dome where it will clear the canopy.
An easy option would be to build a cob oven and enclose it in a 'kennel' to weatherproof it and hide any ugly flue routing we might have to do, with loose fill insulation.
Unfortunately we don't quite have the space at the back of the oven for an enclosure without interfering with existing hard landscaping.
I am proposing hybrid design, using a basic 2:1 sand:fireclay mix 'cast' over a sandcastle dome form to create a 55mm thick oven inner.
This will be sitting on standard 64mm firebricks on 50mm ceramic board insulation.
The clay thermal mass layer would be dried completely before adding 25-50mm ceramic blanket insulation and a layer of cement + aerated clay 'aeorcrete' for more insulation and protection.
The outer layer would be 100mm thick and incorporate ducting the flu from the ideal position up to the top of the dome and a twin wall chimney.
If I am able to get this layer tidy and waterproof I would not add any render. If needs be the whole thing will also be rendered.
I am hopeful I can make the aerocrete layer so that it could be removed if we had cast replacement clay dome.
As I understand it because of the shrinkage of clay ovens and the fact that they aren't actually fired at ceramic temperatures it is normal to add any outer layers before the inner has dried and let thewole lot slowly dry out together. I am hoping that by 'uncoupling' the clay layer from the concrete outer with the ceramic blanket I can wait until the clay has done all of it's shrinking before moving on to create the outer layer, thereby having more control of dimensions.
Apologies for the long first post. I have attached a sketch of the design and welcome comments and advice.
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